Japan's 5G market has come alive, sparked by the aggressive challenge to incumbents by greenfield operator Rakuten.

SoftBank Corp has announced it would offer 5G from March 27 with the debut of four new 5G handsets.

It is Japan's first commercial 5G service. SoftBank will launch in a handful of areas and progressively expand across major cities such as Tokyo, Osaka and Nagoya, NHK reports.

The two biggest operators, NTT DoCoMo and KDDI, have yet to unveil their 5G timetables, but both look set to start service as early as this month.

SoftBank's 5G service will be sold as an add-on to its existing 1,000 yen ($9.35) per month plan, Bloomberg reports. Currently SoftBank, Japan's number three operator by subscriber numbers, sells its 50GB 4G plan for 6,500 yen.

SoftBank's advance into 5G comes just two days after Rakuten unveiled prices for its much-anticipated 4G service at around half existing tariffs. (See Japan's Rakuten gives new meaning to 'bill shock'.)

Rakuten, a unit of Japan's biggest e-commerce and online retail firm, has already garnered 2.3 million customers on its MVNO network. It is prepping for a 5G launch in June.

Marc Einstein, chief telecommunications and digital services analyst at ITR Corp Japan, pointed out that the 5G handsets SoftBank is taking to market – LG, ZTE, Sharp and Oppo – are not the biggest brands in the Japan market.

"It will be more interesting to see what they do with the iPhone when it comes."

He added that with 5G delivering speeds of between 500 Mbit/s and 1 Gbit/s, current data limits won't last long. "We will need to see next-generation plans at some point."

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He said the sums for Rakuten's plan to invest $5.5 billion and hit 15 million subs by 2028 "don't add up."

He told Light Reading: "Their response is mobile will be a loss leader for other services. Interesting concept but still very much needs to be proven."

Einstein was also cautious about Rakuten's virtualized network approach, which it claims will slash operating cost as much as 50-60%. (See Japan's Rakuten Mobile to avoid grand entrance in October.)

"I am not sure that all these network functions are ready to be automated. Consumer feedback on network QoS, customer service etc. is what is going to decide their fate. They need to move quickly as the big three will offer 5G way ahead of them."

Market leader NTT DoCoMo has foreshadowed a 5G video streaming service due to start this month. KDDI has also said it would offer its first 5G service in March, but has offered no details.

Last year, under pressure from the government, DoCoMo attacked the market on price but got little traction.

Einstein forecasts that while rivals compete to cut charges, DoCoMo would aim to move to a new pricing structure. "I think they will try to avoid pure price competition and instead will get more generous with data, perhaps even moving towards unlimited."

— Robert Clark, contributing editor, special to Light Reading